KNOW YOUR BUGS
NATURAL CONTROL OF insect pests comes
from a range of beneficial organisms. Birds can
prey on insects, parasites can feed on an insect's
body, larvae or eggs, bacteria, fungi and viruses
attack, poison and cause disease, and other insects
can compete for food and breeding sites. There
are also many predatory insects and mites that
prey directly on populations of insect pests.
The following are some of the most common
-- and valuable -- beneficial species found in the
winter-rainfall-dominated, dryland cropping regions.
Ladybird beetles
Ladybird adults and larvae
are predatory and consume
prey. Adults and larvae range
from 3 to 7 millimetres in
length, depending on species.
Pests attacked: aphids,
leafhoppers, thrips, mites, moth
eggs and small larvae
Spiders
Spiders are arachnids, not
insects. They consume
adult insects and larvae.
There are many groups
of spiders that commonly
occur in field crops,
including wolf and huntsman
spiders, which chase
Benefiting from nature
With knowledge and correct management, beneficial organisms can play an important part
in successful integrated pest management (IPM) By Paul Umina
down their prey, and trapdoor spiders, which lie
in wait to grab prey walking past their burrows.
Pests attacked: most insects and mites, including other
predators
Predatory mites
There are many predatory mites found in pastoral and
cropping environments in southern Australia. Adult
snout mites are 2mm in length and are generalist
predators that are
particularly effective
in autumn and winter
and can prevent
pest outbreaks.
Nymphs are similar,
but smaller, and
have six legs. They
have lifecycles
that coincide
with their prey.
Pests attacked: earth
mites and lucerne flea
Lacewings
Brown and green
lacewings are very
effective predators
of a range of pests.
The predatory larvae
(8mm) of the green lacewing drive their jaws into
soft-bodied insects or eggs before sucking up the
Mites pose curly question
Researchers and agronomists are rethinking strategies for the study of wheat curl mite,
following the discovery of a new species of the mite By Paul Umina and Ary Hoffmann
PHOTOS: DR ANDREW WEEKS, CESAR CONSULTANTS
LITTLE IS KNOWN in Australia about
wheat curl mite (Aceria tosichella),
the organism primarily responsible
for transmitting the wheat streak
mosaic virus (WSMV). The first case
of WSMV was definitively identified
for the first time in Australia in 2002.
The discovery, by researchers at the
Centre for Environmental Stress and
Adaptation Research (CESAR), of
a second species of wheat curl mite
further complicates the situation.
A DNA diagnostic test has been
developed by CESAR to distinguish
between species of wheat curl mite in
Australia. Attempts to separate the species
by appearance have so far failed.
Surveys show both species of wheat
curl mite are widely distributed within
Australia. It is still unclear whether one
or both species are vectors of WSMV.
What is known about the mites is that
they are highly specialised microscopic
organisms that typically colonise the
youngest tissue of a wheat plant. They
are wingless, cigar-shaped, about
0.2 millimetres long and vectors acquire
WSMV when feeding on infected plants.
Wheat curl mite alone will not
typically cause severe damage to a
wheat plant. However, when population
sizes become large, their presence can
be identified by a longitudinal rolling
GROUND COVER INTEGRATED PEST MANAGEMENT
4
LADYBIRD BEETLE
WOLF SPIDER
LACEWINGS
SNOUT MITE